so i have finished builidng my cannon... i finally found a schrader valve, screwed it in, filled it to 30 psi with nothing in the barrel for a dry shot, and nothing happened... i dont know where i could have gone wrong, but i think it has something to do with my modding of the sprinkler valve or blow gun

i drilled a hole in the top center of the valve, and connected the blowgun, putting everything back inside like it came... is that enough?